<script>
    var str = 'AbC123abc456';
    var reg = /abc/i;    
    reg.exec(str);      
  </script>
  
  <script>
    var str = "It's is the shorthand of it is";
    var reg1 = /it/gi;
    str.match(reg1);    
    var reg2 = /^it/gi;
    str.match(reg2);    
    var reg3 = /s/gi;	
    str.match(reg3);   
    var reg4 = /s$/gi;
    str.match(reg4);    
  </script>